超声波技术用于薏米根多糖的提取

本文采用薏米根为原料，通过单因素考察及正交实验优化了用超声波法提取薏米根多糖的工艺条件。结果表明：超声60min，超声波功率200W，提取温度80℃，固液比1：20为最佳工艺条件。与传统水煎煮法比较，超声波提取方法提取率高，是薏米根多糖提取的一种优选方法。     

参根周皮层锈斑有机组分来源的探讨

本文采用熊田法比较研究了白皮 /红皮参根周皮层提取物的组分。结果表明 ,红皮参根周皮层确实存在具有天然腐殖物质一般特性的有机化合物———类腐殖质物质。参根周皮层死亡组织的分解及其腐殖化是这类物质的重要来源之一。为认识参根锈斑物质的形成提供了新资料     

Ultrastructural localization of nucleic acids in plant tissues following the use of malachite green or neutral red in the fixative solution

Malachite green and neutral red, when added to glutaraldehyde for fixation of various tissues, yielded high-contrast images of cell ultrastructure. Malachite green, in acid conditions, appeared to increase contrast of heterochromatin material in the nucleus whereas neutral red gave greater clarity to the nucleolus and to cytoplasmic ribosomes. Control tissue fixed under acid conditions showed little damage but there were ‘crystalline’ areas at the periphery of the nucleolus. RNase did not digest cytoplasmic ribosomes from tissue after neutral red glutaraldehyde fixation. These results suggested that neutral red became bound to RNA in the tissues. Fixation with malachite green, at a pH below 6, did not affect the digestion of RNA by RNase but did protect chromatin against the bleaching action of the chelating agent EDTA. The addition of malachite green (pH < 6) or neutral red to glutaraldehyde are useful techniques for the investigation of the ultrastructure of nuclear material and cytoplasmic ribosomes.     

英语术语词的可辩性

本文论述了英语科技术语的结构、形式、词义之间的联系，其目的是揭示英语词汇的某些基本特点，帮助读者分析、理解并恰当使用科技术语。     

A NOTE ON SQUARE ROOT FILTERING FOR VECTOR AUTOREGRESSIVE MOVING-AVERAGE MODELS

Abstract. A simplified version of the square root Kalman filter is obtained for a vector autoregressive moving-average (VARMA) model. The algorithm is computationally more efficient that the standard square root algorithm and its output can be used to compute the likelihood of a VARMA model accurately.     

In vivo assay of nitrate reductase in tea (Camellia sinensis L.) leaf and root

Assay conditions in vivo for determination of nitrate reductase activity (NRA) in leaf and feeder root tissues of tea bushes (Camellia sinensis L.) were studied. The composition of the incubation mixture, pH, temperature, period of incubation and tea shoot components were varied. Maximum NRA was obtained in leaf with a medium containing 300 mg Polyclar AT with 300 mg leaf disc in 0.1 M phosphate buffer at pH 7-5, 0.02 M KNO₃ in a total volume of 5 ml and incubated for 4 hat 30°C in the dark. Propan-1-ol inhibited NRA in tea leaf and root. Highest activity was found in the first leaf.     

Theoretical range over which bacteria and nematodes locate plant roots using carbon dioxide

A theory used to estimate the smallest relative chemical gradient that is potentially detectable is given approximately byG>(DCR ²t³)^–1/2 whereD is the diffusion constant andC the concentration of the stimulus chemical,R is the effective radius of the receptor, the velocity of the organism, andt the time period within which the organism measures the concentration. Of these factors, time has the strongest influence. Combining this result with available information on gradients of carbon dioxide around roots and behavior of bacteria and nematodes leads to several conclusions. Bacteria can potentially detect carbon dioxide gradients in the layer of water in contact with the root but not further away. In contrast, plant-parasitic nematodes can potentially detect gradients one meter from a single long root fiber and over 2 m from a plant root mass using klinokinesis. A direct approach using klinotaxis can start a few centimeters from a single root fiber and half a meter from a root mass. These differences are due to differences in the time available to measure the concentrations. Increasing the length of a bacterium could increase its ability to detect gradients by reducing its rotational diffusion. Collimating stimuli that serve to maintain a straight path may provide a means of improving chemotaxis by permitting concentration to be measured for longer times during klinokinesis. More accurate predictions can be made when more precise data are available. The analysis is applicable to a wide variety of other organisms and stimuli.     

颈痛颗粒治疗神经根型颈椎病60例临床观察

目的观察颈痛颗粒治疗神经根型颈椎病60例的临床疗效。方法内服颈痛颗粒,采用随机、自身治疗前、后症状和体征积分变化对比。结果总有效率为96.97%,治疗后积分较治疗前明显减少(P<0.01)。结论颈痛颗粒治疗神经根型颈椎病有明显的疗效。     

PWT外自动根焊工艺的应用

介绍了从意大利PWT公司引进的PWT-CWS.02NRT管道全位置自动焊机的组成、工作原理及技术工艺特点,PWT外自动根焊克服了内自动根焊仅适用于固定管径的缺点。结合辽河油田油建二公司对该套设备在西气东输工程中的使用情况,总结了PWT外自动根焊操作要点及施工中的注意事项,对根焊过程中产生的缺陷进行了分析,并提出了处理措施,可供管道焊接技术人员参考借鉴。     

聚合物包覆的硫化镉量子点的制备及其在次氯酸根检测中的应用

次氯酸根(ClO^-)作为消毒剂和漂白剂的有效成分,常用于的人类生产和生活中。在狭小密闭空间内使用含有次氯酸根的消毒剂存在一定安全隐患,同时ClO^-在体内的参与人体的多项生命活动,过量的ClO^-存在于人体会对人体的免疫系统造成极大危害,诱发多种疾病。因此检测ClO^-是十分必要的。本文采用一锅法,以聚乙烯亚胺为配体合成一种硫化镉量子点荧光探针实现对ClO^- 的检测,结果显示,探针对ClO^- 的识别具有较高的选择性和抗干扰能力,其检测范围在0~40 nmol/L,检测限为0.5 nmol/L。